The present invention relates to novel hyperforin derivatives, the use of such derivatives for the treatment of depression and anxiety, and to formulations containing them.
Flowering tops of Hypericum perforatum contain a number of classes of structurally different substances that act directly or indirectly on the central nervous system. In particular, these compounds include hypericin, hyperforin, and dimeric flavones that exert antidepressive and anxiolycic activities on animals and humans. The mechanisms of action of these compounds are different and include anti-MAO action, action on serotonin release, and benzodiazepine-like activity. Hyperforin is one of the main components of the lipophilic fraction of Hypericum perforatum flowering tops and has recently been the subject of numerous studies that establish its important role as an antidepressant. Applicant has discovered that this molecule has serotoninmimetic activity.
Hyperforin is not very stable to typical extraction and storage conditions. WO 97/13489 to Schwabe shows that the hyperforin content of a water-alcohol extract of St. Johns wort falls almost to zero after only a few weeks. WO 97/13489 further recites that in order to obtain stable extracts with a constant hyperforin content, extraction, purification, and storage should be carried out in the presence of antioxidants such as vitamin C and the esters thereof, sulfated amino acids, and the like. The high instability of hyperforin makes the preparation of hyperforin formulations rather difficult.
The invention relates to a compound having the formula: 
wherein R is a saturated or unsaturated, straight or branched, C1-C22 acyl group, optionally having one or more substituents, which can be the same or different, selected from a group consisting of halogen atoms, nitro, amino, C1-C6-alkylamino, di-C1-C6-alkylamino, and C1-C6-acylamino groups; a cycloaliphatic or aromatic acyl residue wherein the aromatic moiety optionally has one or more substituents, which can be the same or different, selected from the group consisting of halogen atoms, hydroxy, methoxy, and amino groups; or a glycidic residue wherein one or more hydroxy groups are optionally alkylated or acylated. The invention also relates to an extract of Hypericum perforatum containing this compound.
The invention further relates to a process for preparing extracts including the compound of formula I. The method involves extracting Hypericum perforatum flowering tops with supercritical CO2 to obtain a lipophilic extract; dissolving the lipophilic extract in aqueous methanol or acetonitrile to form a hydrophilic phase; extracting the hydrophilic phase with aliphatic hydrocarbons to provide a first aliphatic hydrocarbon phase; diluting the hydrophilic phase with water and counter-extracting the phase with aliphatic hydrocarbons to provide a second aliphatic hydrocarbon phase; combining the first and second aliphatic hydrocarbon phases; concentrating the combined first and second aliphatic hydrocarbon phases; treating the concentrate with a reactive derivative of a RCOOH acid or of an ROH sugar, wherein R is a saturated or unsaturated, straight or branched, C1-C22 acyl group, optionally having one or more substituents, which can be the same or different, selected from the group consisting of halogen atoms, nitro, amino, C1-C6-alkylamino, di-C1-C6-alkylamino, and C1-C6-acylamino groups; a cycloaliphatic or aromatic acyl residue in which the aromatic moiety optionally has one or more substituents, which can be the same or different, selected from the group consisting of halogen atoms, hydroxy, methoxy, and amino groups; or a glycidic residue wherein one or more hydroxy groups are optionally alkylated or acylated.
The invention also relates to a pharmaceutical composition including the compound of formula I and a pharmaceutically acceptable carrier or extract. This pharmaceutical composition is further formulated as a soft-gelatin capsule, hard-gelatin capsule, tablet, or suppository. In a preferred embodiment, the composition includes from 5 to 50 mg of the compound. The pharmaceutical composition can also be formulated as a controlled release dosage form. In a preferred embodiment, the composition includes up to 200 mg of the compound.
The invention also relates to a method of treating depression in an animal including administering to an animal the compound of formula I and extracts thereof.
New hyperforin derivatives have been discovered that are stable and more active as antidepressants. The derivatives of the invention have the following formula: 
wherein R is:
a saturated or unsaturated, straight or branched, C1-C22 acyl group, optionally having one or more substituents, which can be the same or different, selected from halogen atoms, nitro, amino, C1-C6-alkylamino, di-C1-C6-alkylamino, C1-C6-acylamino groups;
a cycloaliphatic or aromatic acyl residue in which the aromatic moiety has optionally one or more substituents, which can be the same or different, selected from halogen atoms, hydroxy, methoxy, amino groups;
a glycidic residue in which one or more hydroxy groups are optionally alkylated or acylated.
Preferably the xe2x80x9caromatic acyl residuexe2x80x9d is a benzoyl or cinnamyl residue having one or more amino or alkoxy groups.
Preferably the xe2x80x9cglycidic residuexe2x80x9d is a residue of one sugar bound by an ether bond to the hydroxy group at the 1-position of the pyranosyl or furanosyl ring, with the other hydroxy groups of the sugar optionally methylated or acetylated.
Preferably R is acetyl, monochloroacetyl, butyryl, xcex3-aminobutyryl, p-aminobenzyl, trimethoxybenxyl, trimethoxycinnamyl, xcex2-glucosyl, or xcex2-galactosyl.
The hyperforin derivatives of the invention can be prepared with conventional methods, well know to those of ordinary skill in the art, for acylation or glycosylation of hydroxy groups. For example, hyperforin, either as substantially pure or as an extract enriched in hyperforin, can be subjected to a reaction with acid chlorides or anhydrides of RCOOH acids (copyright) as defined above) in suitable solvents, such as pyridine.
Glycosylations can be carried out using a suitably protected reactive derivative of the desired sugar (ROH), for example xcex1-D-glucopyranosyl bromide tetraacetate.
A particularly convenient aspect of the invention is that the compounds of formula I can be prepared by extracting Hypericum perforatum flowering tops with carbon dioxide under supercritical conditions, subsequently partitioning the extract between solvents, and derivatizing hyperforin in the resulting extract.
Leaves and flowering tops of St. Johns wort, separately or in mixtures, preferably as natural mixtures, are extracted with carbon dioxide in supercritical conditions under pressures of 180 to 260 bars, preferably about 240 bars, and at temperatures of 35xc2x0 C. to 50xc2x0 C., preferably 40xc2x0 C. A lipophilic extract is obtained containing about 50% hyperforin and considerable amounts of xanthones, waxes, fatty acids, and triglycerides. The hyperforin percentage is subsequently increased by dissolving the resulting extract in methanol or in partially aqueous acetonitrile and then extracting the solution with n-hexane or aliphatic hydrocarbons. The hydrocarbon phase also contains undesirable substances which are removed. The hydrophilic phase is then diluted with about equal volumes of water and aliphatic hydrocarbons and the hydrocarbon layers are combined. The extract of St. Johns wort obtained by concentration of the hydrocarbon phase can be used for the preparation of the derivatives as described above.
The derivatives of the invention exert no activity in vitro on receptors, but are particularly active in vivo, exerting strong antidepressive activity that is related to the dosage. In an in vivo test in mice and rats, the compounds of the invention showed a higher activity than hyperforin and Hypericum ethanol or methanol extracts. The escape deficit development test and the inhibition of the ethanol consumption in Sardinia alcohol preferring rats, according to models known in literature, were selected as in vivo tests to verify the antidepressive effect.
In the escape deficit development test, the compounds of the invention showed a higher activity than known extracts and an activity comparable with that of known medicaments such as imipramine. In the escape deficit development test, rats are restrained and subjected to mild, short, unavoidable electric shocks for 50 minutes. This is known as the pre-test. 24 hours later, the rats are tested for their ability to avoid the same stimuli on their tails, in a situation where escape is impossible. A rat on the average makes 26 escapes out of 30 stimuli (naive controls), whereas a rat subjected to pre-test only makes 1 to 3 escapes (ED controls). The reduction in reactivity induced by the pre-test does not take place in rats that are pre-treated for 1 to 3 weeks with antidepressants such as imipramine or fluoxetine. The compounds of the invention, when administered to rats one hour before their exposure to the unavoidable stress, cause an increase in reactivity to the escape test. This increase in reactivity is enhanced when pre-treatment is effected for 1 to 2 weeks.
For example, treatment of rats with a compound of Formula I in which R is acetyl yields the results reported in the following Table:
Statistical analysis: Kruskal-Wallis non parametric
ANOVA KW=13.462 p 0.0012
Hypericum alcoholic extract and
hexane extract vs naive p less than 0.01
Hyperforin acetate 25 mg vs naive n.s.
Naive vs AND p less than 0.01
In a test of the reduction of alcohol consumption (which is an index of depression and anxiety) in Sardinia rats according to procedures known in literature, the compounds of the invention, after a two-day administration, induced a 60% to 75% decrease in alcohol consumption in favor of water compared with controls.
The compounds of Formula I can be formulated in soft-gelatin capsules, hard-gelatin capsules, tablets, or suppositories. Preferably the compounds of the invention are formulated in soft-gelatin capsules or in controlled-release formulations. The dosages of compounds in the formulations are 5 to 50 mg per dose in the usual formulations and up to 200 mg in the controlled-release formulations. The preferred dosage in the controlled-release formulations is 200 mg per dose daily.